The invention relates to a suspension for a rail brake on a bogie of a rail vehicle, as well as to a bogie for a rail vehicle.
Rail brake systems for rail vehicles are conventionally held on the bogie frames on both sides of a bogie. The rail brake has brake anchor plates which are provided on both sides of the wheel sets of the rail vehicle below the bogie frames. In this case, the rail brake is conventionally constructed as an electromagnetic rail brake or as an eddy current brake. Thus, the brake anchor plates may carry brake magnets on their underside, which brake magnets can be displaced by lifting devices between a lowered braking position and a lifted release position. In the lowered operative position, the brake magnets should rest on the surface of the rail or be present at a distance from the surface of the rail which is slight and as constant as possible.
In this case, the rail brakes are suspended in a pendulum fashion and designed such that they permit a lateral play of, for example, 2 to 12 mm, in the case of electromagnetic rail brakes in the low-suspension state, in order to permit a maximal overlapping between the rail brake and the rail corresponding to the axle base and the turning radius. The rail brake also has the tendency to utilize this lateral play also in the release position because accelerations occur in the bogie which, as a result of the inertia of the rail brake, are converted to pendulum movements. This may result in damage to the body.
From German Patent Document DE 197 25 174 A1, a suspension for a rail brake is known, in the case of which the lifting devices are constructed as lifting bellows which are operated pneumatically. For avoiding the pendulum movements of the rail brake in the release position and particularly in order to achieve an uncoupling of the brake with respect to the bogie and thus a positive influence on the running characteristics of the rail vehicle, a rubber layer spring is provided in this construction which centers the rail brake in the release position transversely elastically on the bogie frame. This construction was successful when active lifting devices were used.
If, in contrast, passive systems, such as pressure spring arrangements, are used for the suspension of the rail brake, problems occur in practice when a rubber layer spring is used. As a rule, such pressure spring arrangements are used for electromagnetic rail brakes in a low suspension and are configured such that, with respect to their spring force, the action of current on the electromagnets and, thus, the generating of a magnetic field is sufficient for attracting the rail brake against the force of the pressure spring to the surface of the rail. Here, the magnetic force causes an automatic centering on the rail, and the braking force is transmitted from the brake magnets by way of carriers or pull or push bows to the vehicle. When the rail brake is deactivated, it is displaced, because of the prestressing force of the pressure spring arrangement, back from the braking position into the lifted release position.
While the known centering device with the rubber layer spring in the release position is constantly prestressed by the lifting bellows against the bogie, in the case of a pressure spring arrangement, it may, however, be possible, particularly in the case of impact loads, that the centered and damped position cannot be maintained. This problem is the result of the fact that the spring force of the pressure spring arrangement is a constructively defined value, which in this case is configured such that it can be overcome by the activation of the rail brake. Thus, in the case of a pressure spring arrangement, the rail brake is not as reliably held in the release position as in the case of a spring bellows arrangement actively acted upon by compressed air. On the other hand, pressure spring arrangements are distinguished by their simple construction and ruggedness.
Furthermore, the problem of impact loads increases with the expanded usage range of these braking systems. Thus, pressure spring suspensions have so far mainly been used on streetcars, etc. which move at relatively low speeds. Now, systems of this type are to be used also in the standard gauge railway range, where speed of over 100 km/h are traveled on a regular basis. As a result, the dynamic loads on the rail brake increase significantly. While a rail brake suspended in this manner, when used in a streetcar, could still be sufficiently held also in the release position by providing carriers, so that no damage occurred to the rest of the body, this can no longer be excluded in the case of the intended increased loads.
It is therefore an object of the present invention to further develop a suspension of the above-mentioned type for a rail brake in such a manner that, also when passive lifting devices are used, the movements of the rail brake in the release position can be limited with respect to the bogie and hard impacts can be avoided and the required lateral play is nevertheless permitted in the braking position.
This object is achieved by means of a suspension for a rail brake, according to the present invention, by providing damping elements between the carriers of the bogie frame and the stoppers of the rail brake in the release position of the rail brake to damp forces transverse to the traveling direction of the rail vehicle.
Thus, it was recognized according to the invention that, as a result of astonishingly low constructional expenditures, a significantly improved suspension can be implemented for a rail brake of this type. By means of the further development according to the invention, particularly the expenditures are reduced for the constructive design of the damping elements, mainly with respect to a suitable characteristic curve of the damping characteristics. The suspension according to the invention is therefore distinguished not only by its cost-effective producibility but also by a very high reliability. The susceptibility to damage is therefore low and, by selecting a suitable material, very long service lives can be achieved. This construction is particularly suitable also for a large range of loads, so that use is also possible at very high speeds. Impacts and vibration loads can thereby be reliably absorbed without any damage to surrounding parts of the body.
While in the prior art, even a slight sagging of the rail brake under loads of this type could result in a loss of centering, this can be avoided by the suspension according to the invention because, instead of the rubber layer spring, which has a differentiated springing behavior in each layer, a compact damping element is used. As a result, a high reliability of the system can be achieved.
Because of the simple construction, it is also possible according to the invention to further develop the damping elements without any high constructive expenditures with respect to their material characteristics and dimensioning that they develop a sufficient damping effect in the release position and, in the braking position, nevertheless continue to permit the required lateral play, so that the required braking effect can fully develop, for example, when taking curves.
Advantageous further developments of the invention are as follows.
When the damping elements are arranged on the stoppers of the rail brake, existing arrangements can be retrofitted in a simple manner without requiring any changes on the bogie.
It is also advantageous, in the release position, for the stoppers to be received with a play transversely to the traveling direction in the carriers. As a result, friction forces during the movement of the rail brake from the braking position into the lifted release position can be effectively reduced or completely prevented. An exact method of operation of the rail brake can thereby be achieved in an even better fashion. Furthermore, the wear of the arrangement is reduced, which increases its durability.
As an alternative, it is also possible that, in the release position, the rail brake is centered by the damping elements in the carriers. This construction has the advantage that free movements of the rail brake are essentially completely avoided, whereby the dynamic stressing of the arrangement is further reduced.
The further development with or without play in this case depends essentially on the respective application and the given parameters, such as the desired maximal speed of the rail vehicle, etc.
When the carriers reach in a U-shape around the stoppers, in which case the damping elements are arranged on both sides on the stoppers, a reliable fixation is achieved on each carrier. The stability of the arrangement in the release position is further increased thereby.
As an alternative thereto, it is also possible to construct the carriers in an L-shape and to arrange them such that they receive the rail brake in a horizontal plane. In this case, the rail brake has at least two brake magnets which are arranged parallel to one another under the bogie frames and which are connected by way of only one anchor arm. This construction has the advantage that the carriers can have a simpler design. The degree of freedom in the case of the L-shaped embodiment, which exists in contrast to the U-shaped further development of the carriers, is in this case eliminated by the anchor arm. This prevents a tilting of the brake magnets. This arrangement is also more accessible to servicing and maintenance work.
If the damping elements in this embodiment are in each case arranged only on the side of the stoppers which are oriented to the pertaining carriers, the construction is further simplified. Furthermore, the number of parts subjected to wear can be reduced, whereby the durability of the arrangement is improved.
Because of the fact that a longitudinal damping element is arranged on the stoppers which, interacting with the carriers, damps movements in the traveling direction, an even greater reliability of the arrangement is achieved because loads, etc. in the longitudinal direction can also be reliably absorbed.
According to another aspect of the invention, a bogie for a rail vehicle is provided which contains the suspension according to the invention. By means of this bogie, improved traveling characteristics are achieved and the susceptibility to damage is simultaneously reduced. This also permits a use of such a bogie at speeds above 100 km/h.
In the following, the invention will be explained in detail in embodiments by means of the figures in the drawing.